KR100301989B1 - Method for controlling width of plate during hot rolling of plate - Google Patents

Abstract

PURPOSE: A method for controlling a width of a plate during hot rolling of the plate is provided which obtains an accurate target width of the plate by setting a gap of horizontal rolls considering a length reduction amount of a slab in a width direction by edger rolling and a spread amount of the slab by horizontal rolling in widthwise rolling. CONSTITUTION: In a method for hot rolling a steel slab in which widthwise rolling is performed by edger rolls and horizontal rolls, the method for controlling a width of the slab during hot rolling of the slab comprises the steps of obtaining a variation coefficient of a length of the slab(CL) by the following mathematical expression 4 considering a length reduction amount of the slab in a width direction by edger rolling and a spread amount of the slab by horizontal rolling:£Mathematical Expression 4| where A, B, m, n and r are varied depending on types of steel as regression coefficients for each affecting factors; obtaining a slab length variation(ΔL) by the following mathematical expression 4a:£Mathematical Expression 4a| using the obtained variation coefficient of the length of the slab(CL); obtaining a target widthwise thickness(H*r) by the following mathematical expression 5:£Mathematical Expression 5| using the obtained slab length variation(ΔL); obtaining a gap of horizontal rolls(S'i) by the following mathematical expression 6:£Mathematical Expression 6|£Mathematical Expression 6a| using the obtained target widthwise thickness(H'r); and hot rolling the steel slab in an ordinary manner after setting a gap of the horizontal rolls corresponding to the obtained gap of the horizontal rolls(S'i).

Description

Plate width control method during hot thick plate rolling

1 is a schematic diagram showing a thick plate rolling process

(A) of FIG. 2 is an open-circuit diagram which shows a breadpot rolling process.

(b) is sectional drawing along the line A-A of FIG. 1 (a).

(c) is sectional drawing along the B-B line | wire of FIG.

3 is a schematic view showing a thick plate rolling process

4 is a tube width control flow chart during hot plate rolling in accordance with the present invention.

* Explanation of symbols for main parts of the drawings

1: slab 2: edge roll

3: horizontal roll

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate width control method for rolling to a target plate width in thick plate rolling, and more particularly, to a breadboard rolling using an edge roll and a horizontal roll. In the roll width control method for hot thick plate rolling, in which the roll gap is set in consideration of the reduction in the slab length in the width direction due to the edge rolling and the spread amount due to the horizontal rolling, It is about.

In the conventional thick plate rolling process, as shown in FIG. 1, the slab 1 is subjected to even rolling in one or two passes, rotated by 90 °, and then rolled in three to eight passes. After rotating to 90 ° original state, the final plate product is manufactured through a lengthwise rolling process of 6-16 passes. At this time, the width of the product is determined by the bread width rolling process.

However, when thick plate rolling is performed by the above-described conventional method, the slab 1 rotated by 90 ° has a phenomenon in which the slab length decreases in the width direction by edge rolling or the slab length increases due to thickness rolling. There is a problem in that it is difficult to manufacture a target plate width after the rolling is finished.

The breadth rolling target thickness (Hr) to obtain the breadth rolling target plate width is given by the following equation (1)

Is expressed. Here, H _o , W _o , L _o represent the slab thickness, width, and length before the bake rolling, and H _r , W _r , L _r represent the target thickness, the target plate width, and the length after the bake rolling, respectively. . Assuming that there is no change in the slab length in the width direction before and after the width rolling in Equation (1), the target thickness H _r after rolling is expressed by the following expression (2).

Is expressed. When the target thickness is obtained in Equation (2), in consideration of the elastic recovery amount (δ _i ) according to the thickness rolling pass schedule in the width-exposure rolling process, the horizontal roll opening degree S _{i for} each pass as shown in Equation (3) below. ) Will be set.

Here, n is the number of rolling passes bet width, β _i is i pass meet baebunyul, △ H _i is the reduction ratio i pass thickness.

The roll opening control method by calculating the target thickness of the conventional breading machine does not consider the influence of the decrease of the slab length in the width direction due to the edge rolling during the breading roll and the spreading amount due to the thickness rolling. There is no problem.

Accordingly, the present inventors conducted research and experiments to solve the problems of the conventional method described above, and based on the results, the present invention proposes the present invention. Hot rolled plate rolling that can obtain accurate target plate width by setting horizontal roll gap in consideration of reduction of slab length in the width direction by edge rolling and spreading by horizontal rolling It is to provide a width control method, which has a purpose.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

According to the present invention, in the hot rolling method of steel slab subjected to the width rolling by the edge roll and the horizontal roll, the slab length variation coefficient in consideration of the amount of slab length reduction in the width direction by the edge rolling and the spread amount due to the thickness rolling ( Obtaining C _L ) by the following formula (4);

(Where A, B, m, n and r are regression coefficients for each influencer, which are values that change with the steel grade)

Obtaining a slab length change amount _ΔL by the following equation (4a) using the slab length change amount coefficient C _L obtained as described above;

Obtaining an exploding target thickness (H _r ^* ) by the following equation (5) using the slab length variation (Δ L) obtained as described above;

Obtaining a horizontal roll opening degree (S _i ^* ) by the following formula (6) using the obtained breading target thickness (H _r ^* ); And

It relates to a sheet width control method for hot thick plate rolling comprising the step of setting the opening degree of the horizontal roll corresponding to the horizontal roll opening degree (S _i ^* ) obtained as described above, and then hot rolling the steel slab in a conventional manner. .

Hereinafter, the present invention will be described in detail.

The present invention is applied to the hot rolling method of steel slab (I) which performs breading rolling by the edge roll (2) and the horizontal roll (3), as in FIGS.

4 will be described in detail a method of controlling the width of the hot plate during hot rolling.

As shown in Figure 4, in order to control the plate width according to the present invention, it is necessary to obtain the slab length variation coefficient C _L as shown in Equation (4).

Where Δ L _e is the edging amount due to the edge rolling, C _L is the slab length change in the width direction after the breading roll, and A, B, m, n, r are the regression coefficients for each influence factor. It is a changing value.

Next, using the slab length change coefficient C _L calculated | required above, the slab length change amount before and after bread-making rolling is calculated | required by following formula (4a).

Next, using the slab length change amount (ΔL) obtained as described above, the target thickness of exposing by the following formula (5) Obtain

(Where W ₀ and L ₀ represent the slab width and length before the rolling process)

In the above, the target thickness Denotes the corrected target thickness in consideration of the amount of change in the slab length in the width direction before and after the breadboard rolling.

W ₀ and L ₀ may be measured from the width measuring sensor 4 as shown in FIG.

Next, the breadth target head calculated as described above. Horizontal roll opening degree by the following formula (6) Obtain

Next, the horizontal roll opening obtained as described above By setting the opening degree of the horizontal roll correspondingly to and then hot-rolling the steel slab in a conventional manner, a hot post-rolled sheet having a more accurate target plate width is produced.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

Applying the plate width control method of the present invention to investigate the width-weight ratio, deviation between the width of the plate width, the results are shown in Table 1 below.

The material used was 566 sheets, and the width value was measured from the width measurement sensor.

TABLE 1

As shown in Table 1, when applying the present invention it can be seen that the target plate width hit ratio and plate-to-plate variation can be reduced more effectively than before application.

As described above, the present invention has an effect of further improving the error rate of the thick plate product by more precisely controlling the plate width in consideration of the amount of change in the slab length in the width direction in the bread-making rolling process.

Claims (1)

In the hot rolling method of steel slab, which is rolled by edge roll and horizontal roll, slab length variation factor (C _L ) considering the amount of slab length reduction in the width direction by edge rolling and the amount of spread by thickness rolling To obtain the understanding in the following formula (4); (Where A, B, m, n and r are regression coefficients for each influencer, which are values that change with the steel grade) Obtaining a slab length change amount? L by the following formula (4a) using the slab length change amount coefficient C _L obtained as described above; Target thickness of exploding by following formula (5) using slab length change amount (DELTA) L calculated | required as mentioned above. Obtaining a; Target thickness Horizontal roll opening degree by the following formula (6) Obtaining a; And The horizontal roll opening obtained as described above And setting the opening degree of the horizontal roll according to the method, and then hot rolling the steel slab in a conventional manner.